The present invention relates generally to a method for injection molding a pump impeller, as well as to a pump impeller manufactured accordingly.
Pump impellers, in particular impellers of centrifugal pumps or rotatory pumps, typically include a plurality of blades, between which channels are defined, which extend from the center of the impeller to the outer periphery, usually along a curved path. With closed impellers, the blades are thereby formed between two cover plates which are distanced to one another, so that the flow channels at least in a section are only open to the inner periphery and to the outer periphery of the impeller.
The manufacture of such impellers is quite complicated, since the cavities which define the flow channels between the blades, may not be formed without further ado. It is thus known to compose the impellers of several parts, be they of plastic or metal. Thus, the blades may be formed on a cover plate, and then for example the second cover plate may be welded onto the end-edges of the blades. With such a design, the cover plate with the blades may also be manufactured in an inexpensive manner as a cast part, be it of metal or plastic. If a closed impeller is to be manufactured as one piece as a cast part, until now this was only possible with the help of a lost cores, since on account of the geometry of the flow channels, which is optimized with regard to flow technology, undercuts arise in these channels, which prevent the withdrawal of the cores in the longitudinal direction of the flow channels.
For reasons of cost, it is however desirable to cast such impellers as one piece, for example as injection molded parts of plastic. Thus, further assembly steps which are required for putting together multi-part impellers are done away with.